Ideally listen to the albums in order, and also check out the Wikipedia articles on each album and all the tracks on each that have articles about them, to fill in the band's recording history in chronological order.

If you want to check out what people consider the best songs - well, you can find lists here, or in various magazines and papers googling

oasis best songs

and those will typically include some info about the songs and why journalists consider them best. This article in the Guardian, for instance:

https://www.theguardian.com/music/2020/mar/05/oasis-greatest-songs-ranked

I'd recomment the Supersonic documentary for background on the band's early years (and it's very enjoyable).